1. Technical Field
The present invention relates to surgical cutting and stapling instruments and, in various embodiments, to disposable surgical staple cartridges.
2. Background
Endoscopic surgical instruments are often preferred over traditional open surgical devices since a smaller incision tends to reduce the post-operative recovery time and complications. Generally, these endoscopic surgical instruments include an “end effector”, a handle assembly and an elongated shaft that extends between the end effector and the handle assembly. The end effector is the portion of the instrument configured to engage the tissue in various ways to achieve a desired diagnostic or therapeutic effect (e.g., endocutter, grasper, cutter, staplers, clip applier, access device, drug/gene therapy delivery device, and energy device using ultrasound, RF, laser, etc.).
Two primary design approaches have been used in the past by various medical component manufacturers to reduce the overall cost of endoscopic surgical instruments such as endocutters. While both attempts have been successful at addressing at least some of the user's needs, neither attempt has fully addressed all of those needs.
For example, the first design approach concerned the use of a disposable endocutter devices for each firing. Such endocutter end effectors were fabricated from relatively weak components that can only be fired once before a new end effector is required since the end effector components are markedly deformed after each firing. This type of end effector employed an “I-beam” feature on the knife to prevent the anvil from deflecting away from the cartridge during firing. Since the I-beam is riding on a relatively weak anvil component, the I-beam deforms the portion of the anvil located directly underneath the I-beam feature. This combination of factors allows staple form to be improved while decreasing the forces required to actuate the device because the I-beam is only pulling the anvil material down to the correct position relative to the cartridge where it's needed to form a staple at any given time.
While this approach improves staple form and lowers the force required to cut the tissue and deploy the staples, it has a number of disadvantages. First, having the surgeon dispose of an entire anvil, channel and cartridge after each firing adds a great deal of manufacturing expense. Second, the device often doesn't securely clamp the targeted tissue due to a combination of the relatively weak end effector components and the manner in which the anvil is actually clamped onto the tissue. The third issue is that the relatively weak end effector components can only reliably be used to fire on moderate tissue thicknesses and the components will not function on very thick tissues.
The second primary design approach taken in the past is to make much stronger end effector components that can be used for multiple firings. In this approach, only the cartridge assembly is replaced after each firing. Because the end effector components have to resist multiple firing loads, they are purposefully designed such that they do not deform after each firing. This design concept employs a different set of features on the knife to keep the anvil positioned relative to the cartridge during deployment of the staples to improve staple form. The combination of the stiffer end effector components and a different clamping mechanism allows this type of device to reliably exert high clamping loads so the surgeon can easily manipulate the desired tissue. The stiffer components also allow the end effector to be reliably used on relatively thick tissue samples.
One disadvantage of this approach, however, is that the features on the knife that prevent the anvil from deflecting away from the cartridge are now required to pull a very stiff anvil component down towards the cartridge. The knife is therefore attempting to pull an entire beam down towards the cartridge that is as long as the entire staple line instead of just pulling the anvil down in a localized region as on the previous device. This approach, therefore, generally must generate higher deployment forces due to the increased anvil drag loads on the knife.
U.S. Patent Publication No. US 2007/0175950 A1, entitled “Disposable Staple Cartridge Having an Anvil With Tissue Locator For Use With Surgical Cutting and Fastening Instrument and Modular End Effector System Therefor”, the disclosure of which is herein incorporated by reference in its entirety, discloses various disposable cartridge arrangements that employ a disposable anvil component. Such arrangement effectively address a variety of the shortcomings discussed above, but also include the additional expense of an anvil component. In addition, all of the foregoing arrangements require a separate support channel for supporting the staple cartridge therein. Such support components add to the expense of the surgical instrument.
Consequently, there is a need for a surgical staple cartridges that effectively address many of the shortcomings described above.
The foregoing discussion is intended only to illustrate some of the shortcomings present in the field of the invention at the time, and should not be taken as a disavowal of claim scope.